Numerical analysis has been carried out to evaluate the ductile fracture in an overmatched welded joints case using a standard CT specimen. These investigations have been performed by analysing the monometallic, bimetallic and trimetallic configurations in order to compare global approaches (i.e. the J integral and CTOD) with a local approach (Rice and Tracey model). The different cases lead to a globally similar evolution of CTOD and of the J integral. These two parameters are not really affected when changing the configuration while the void growth ratio (R/Ro) is very sensitive to the strain and strain fields around the crack tip. Furthermore, according to the parameter (R/Ro) distribution at the crack tip, it seems possible to predict the crack propagation direction in the overmatched welded joints case.